﻿
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<!-- saved from url=(0014)about:internet -->
<html xmlns:msxsl="urn:schemas-microsoft-com:xslt" xmlns:mssdk="winsdk" xmlns:script="urn:script" xmlns:build="urn:build" xmlns:MSHelp="http://msdn.microsoft.com/mshelp">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
<meta name="Description" content="The question mark (?) command evaluates and displays the value of an expression.Note   A question mark by itself (?) displays command help."/>
<meta name="MSHAttr" content="PreferredSiteName:MSDN"/>
<meta name="MSHAttr" content="PreferredLib:/library/windows/hardware"/>
<title>? (Evaluate Expression)</title>

<meta name="MS-HAID" content="r15_cmds_A_c6ea44eb-73b8-451d-8054-ded9b17ac2bd.xml"/>


<link rel="STYLESHEET" type="text/css" HREF="../common/backsdk4.css"/>





<style>
html,div { margin: 0; padding: 0;}

body {
	padding: 0px;
	margin: 0px;
	overflow: auto;
	height: 100%;
}

#winchm_template_button{
	float: right;
	width: 93px;
	top: 7px;
	position: relative;
	text-align: right;
	right: 5px;
	height: auto;
}

#winchm_template_top{
	padding: 0px;
	margin: 0px;
	border-bottom: 1px solid #9B9B9B;
	background-color: #B1CEFE;
}

#winchm_template_navigation{
	margin: 0px;
	padding-top: 7px;
	padding-left: 7px;
	padding-bottom: 3px;
	padding-right: 0px;
	font-size: 8.5pt;
	font-family: Arial, Helvetica, sans-serif;
	font-weight: normal;
	color: #585858;
}

#winchm_template_title{
	margin: 0px;
	padding-top: 4px;
	padding-left: 7px;
	padding-bottom: 7px;
	padding-right: 0px;
	font-size: 18px; 
	font-family: Verdana, Geneva, sans-serif;
	color: #363636;
}

#winchm_template_content{
	margin-top: 20px;
	margin-left: 15px;
	margin-bottom: 20px;
	margin-right: 15px;
	width: auto  !important;
	width: 100%;
}

#winchm_template_footer{
	border-width: 1px;
	border-color: #B1CEFE;
	border-top-style: solid;
	margin-top: 15px;
	margin-left: 15px;
	margin-bottom: 20px;
	margin-right: 15px;
	padding-top: 7px;
	padding-left: 0px;
	padding-bottom: 0px;
	padding-right: 0px;
	font-family: arial, helvetica, sans-serif;
	font-size: 8.5pt;
	color: #696969;
	width: auto;
	text-align: left;
}


#winchm_template_container{
	margin: 0px;
	padding: 0px;
	position: static;
	padding-bottom: 3px;
	overflow: auto;
	background-color: #FFFFFF;
}


@media print
{
#winchm_template_container{
	position: static;	
	margin: 0px;
	padding: 5px;
	
	width: auto;
	height: auto;
	overflow: auto;
}
#winchm_template_button{
visibility:hidden;
}
}

#winchm_template_navigation A:link	{text-decoration: none; color:#004080}
#winchm_template_navigation A:visited  {text-decoration: none; color: #004080}
#winchm_template_navigation A:active {text-decoration: none; color: #004080 }
#winchm_template_navigation A:hover {text-decoration: none;color: #0080FF}

A:link	{text-decoration: underline; color:#0033CC}
A:visited  {text-decoration: underline; color: #0033CC}
A:active {text-decoration: underline; color: #0033CC }
A:hover {text-decoration: underline;color: #FF0000;}
</style>
<script type="text/javascript">
function isMobile(){
Agent = window.navigator.userAgent;
if (Agent.indexOf("iPhone")>=1 || Agent.indexOf("iPad")>=1 || Agent.indexOf("iPod")>=1 || Agent.indexOf("Android")>=1){
return true;
}else{
return false;	
}

}
function d_onresize(){
if (window.navigator.userAgent.indexOf("MSIE")>=1){
document.getElementById('winchm_template_container').style.pixelWidth = document.body.offsetWidth - 3;
document.getElementById('winchm_template_container').style.pixelHeight = document.body.offsetHeight - document.getElementById('winchm_template_top').offsetHeight - 4;
}
document.getElementById('winchm_template_container').style.top = document.getElementById('winchm_template_top').offsetHeight + 'px';
}

function d_onbeforeprint(){
document.getElementById('winchm_template_container').style.width = 'auto';
document.getElementById('winchm_template_container').style.height = 'auto';
}

function d_onafterprint(){
d_onresize();
}

if(!isMobile()){

window.onload = d_onresize;
window.onresize = d_onresize;
window.onbeforeprint = d_onbeforeprint;
window.onafterprint = d_onafterprint;

document.write("<style>\n");
document.write("body {overflow: hidden;}\n");
document.write("#winchm_template_container {position: absolute;overflow: auto;top : 0px;right: 0px;bottom: 0px;left: 0px;}\n");
document.write("</style>\n");
}

</script>
</head>
<body><script language="JavaScript" type="text/JavaScript">
function syn(){
if(parent.nav.tree){
 if(parent.nav.tree.loaded){
  parent.nav.tree.selectNode(1955);
 }else{
  setTimeout("syn()",500);
}
  }else{
  setTimeout("syn()",500);
  }}
if(parent!=self){
  setTimeout("syn()",100);
}else{
  parent.location.href = "../../index.htm?page=debugger/___evaluate_expression_.htm";
}
originalOnload = window.onload;
if(originalOnload==null){
window.onload = function(){parent.contentLoaded = true;};
}else{
window.onload = function(){originalOnload();parent.contentLoaded = true;};
}
</script> 


<div id="winchm_template_top">
	<div id="winchm_template_button"><A href="___command_help_.htm" title="Previous topic"><img id="winchm_template_prev" alt="Previous topic" src="../template2/btn_prev_n.gif" border="0"></a><A href="____evaluate_c___expression_.htm" title="Next topic"><img id="winchm_template_next" alt="Next topic" src="../template2/btn_next_n.gif" border="0"></a></div>
	<div id="winchm_template_navigation">Help &gt; 
<A href="introduction6.htm">Debugging Tools for Windows (WinDbg, KD, CDB, NTSD)</A> &gt; <A href="debugger_reference.htm">Debugger Reference</A> &gt; <A href="debugger_commands.htm">Debugger Commands</A> &gt; <A href="commands.htm">Commands</A> &gt; </div>
	<div id="winchm_template_title">? (Evaluate Expression)</div>
</div>
<div id="winchm_template_container">
	<div id="winchm_template_content"><div id="mainSection"><p>The question mark (<b>?</b>) command evaluates and displays the value of an expression.</p>
<div class="alert"><b>Note</b>    A question mark by itself (<a href="#Bookmark1954"><b>?</b></a>) displays command help. The <b>?</b> <i>expression</i> command evaluates the given expression.</div>
<div> </div>
<pre class="syntax"><b>? </b><i>Expression</i></pre>
<h2><a id="ddk_cmd_evaluate_expression_dbg"></a><a id="DDK_CMD_EVALUATE_EXPRESSION_DBG"></a>Parameters</h2>
<p></p>
<dl>
<dt><a id="_______Expression______"></a><a id="_______expression______"></a><a id="_______EXPRESSION______"></a>       <i>Expression</i>      </dt>
<dd>
<p>Specifies the expression to evaluate.</p>
</dd>
</dl>
<h3><a id="Environment"></a><a id="environment"></a><a id="ENVIRONMENT"></a>Environment</h3>
<table>
<tr>
<td>
<p><b>
          Modes</b></p>
</td>
<td>
<p>User mode, kernel mode</p>
</td>
</tr>
<tr>
<td>
<p><b>
          Targets</b></p>
</td>
<td>
<p>Live, crash dump</p>
</td>
</tr>
<tr>
<td>
<p><b>
          Platforms</b></p>
</td>
<td>
<p>All </p>
</td>
</tr>
</table>
<p> </p>
<h2>Remarks</h2>
<p>The input and output of the <b>?</b> command depend on whether you are using MASM expression syntax or C++ expression syntax. For more information about these kinds of expression syntax, see <a href="#Bookmark1266">Evaluating Expressions</a> and <a href="#Bookmark1917">Numerical Expression Syntax</a>.</p>
<p>If you are using MASM syntax, the input and output depend on the current radix. To change the radix, use the <a href="#Bookmark2015"><b>n (Set Number Base)</b></a> command.</p>
<p>The <b>?</b> command evaluates symbols in the expression in the context of the current thread and process.</p>
<p>Some strings may contain escapes, such as <b>\n</b>, <b>\"</b>, <b>\r</b>, and <b>\b</b>, that are meant to be read literally, rather than interpreted by the evaluator.  If an escape within a string is interpreted by the evaluator, errors in evaluation can occur.  For example:</p>
<div class="code"><span codelanguage=""><table>
<tr>
<th></th>
</tr>
<tr>
<td>
<pre>0:000&gt; as AliasName c:\dir\name.txt
0:000&gt; al
  Alias            Value
 -------          -------
 AliasName        c:\dir\name.txt
0:001&gt; ? $spat( "c:\dir\name.txt", "*name*" )
Evaluate expression: 0 = 00000000
0:001&gt; ? $spat( "${AliasName}", "*name*" )
Evaluate expression: 0 = 00000000
0:001&gt; ? $spat( "c:\dir\", "*filename*" )
Syntax error at '( "c:\dir\", "*filename*" )</pre>
</td>
</tr>
</table></span></div>
<p>In the first two examples, even though the string does match the pattern, the evaluator is returning a value of <b>FALSE</b>.  In the third, the evaluator cannot make a comparison because the string ends in a backslash ( \ ), and so the <b>\"</b> is translated by the evaluator.</p>
<p>To get the evaluator to interpret a string literally, you must use the <b>@"</b><i>String</i><b>"</b> syntax.  The following code example shows the correct results:</p>
<div class="code"><span codelanguage=""><table>
<tr>
<th></th>
</tr>
<tr>
<td>
<pre>0:000&gt; ? $spat( @"c:\dir\name.txt", "*name*" )
Evaluate expression: 1 = 00000000`00000001
0:000&gt; ? $spat( @"${AliasName}", "*name*" )
Evaluate expression: 1 = 00000000`00000001
0:001&gt; ? $spat( @"c:\dir\", "*filename*" )
Evaluate expression: 0 = 00000000</pre>
</td>
</tr>
</table></span></div>
<p>In the preceding examples, the <b>$spat</b> MASM operator checks the first string to determine whether it matches (case-insensitive) the pattern of the second string.  For more information about MASM operators, see the <a href="#Bookmark1918">MASM Numbers and Operators</a> topic.</p>
<h2><a id="see_also"></a>See also</h2>
<dl>
<dt><a href="#Bookmark1956"><b>?? (Evaluate C++ Expression)</b></a></dt>
<dt><a href="#Bookmark2115"><b>.formats (Show Number Formats)</b></a></dt></dl></div></div>	
	<div id="winchm_template_footer">Copyright &copy; 2019. All rights 
reserved. (To change the copyright info, just edit it in template.)</div>
</div>

</body>
</html>
